Arrangement for tipping a table

ABSTRACT

The invention relates to a tilting table array for micro-positioning objects, preferably for defined generation of oscillating movements of optical objects, such as for instance mirror elements in projection lens arrays, including a tilting table carrying the object and connected to at least one drive element as well as a tilting table housing that is coupled to the tilting table via an elastic connection. According to the invention, the tilting table, the tilting table housing and the elastic connection comprise one monolithic unit.

FIELD OF THE INVENTION

The invention relates to a tilting table array for micro-positioningobjects, preferably for defined generation of oscillating movements ofoptical objects, such as for instance mirror elements in projection lensarrays, including a tilting table carrying the object and connected toat least one drive element as well as a tilting table housing that iscoupled to the tilting table via an elastic connection.

BACKGROUND OF THE INVENTION

DE 19700580 A1 describes a tilting table array for micro-positioningmirror elements in which a tilting movement of the mirror elements abouttwo tilting axes is achieved by means of solid body joints attached to abase plate. Such arrays are very complicated in structure and thereforehighly cost-intensive. Moreover, the serviceable life is relativelyshort due to wear phenomena that occur.

Tilting table arrays are also known in which an object carrier isconnected to a tabletop via, for example, a rotating or tilting joint.The object carrier is tilted about the rotating joint using piezoelements that are arranged in the tabletop and in the object carrier atdefined intervals from the rotating joint. Such an array is described inDE 19606913 C1, for example.

The disadvantage of all known arrays is that the complexity ofassembling a device system is relatively high, because, in the majorityof applications, it is necessary to affix and adjust the array in anadditional housing.

This results in a large number of individual parts being needed formicro-positioning, which is associated with high complexity for makingthe adjustments and, therefore, significant costs, so that such arraysprove to be disadvantageous, particularly in mass production.

Based on the above, the object of the invention is to further develop atilting table array for static or dynamic micro-positioning of objectssuch that virtually wear-free, highly accurate and cost-minimizedpositioning of an object is possible with relatively few individualelements.

SUMMARY OF THE INVENTION

This object is inventively achieved using a tilting table array of thetype described initially in that the tilting table, the tilting tablehousing, and the elastic connection comprise one monolithic unit,wherein the elastic connection can be at least one bending element or atleast one torsion element or at least a combination of both elements.

Because of the fact that the key functional elements of the tiltingtable array comprise one component, only a few individual elements areneeded for micro-positioning an object.

In this connection, the monolithic unit can consist of either a metallicor a non-metallic material, and is usefully an injection molded part, adie-cast part or a combination of several shaping methods.

Dimensional variances in the array result solely from tool-relatedshaping tolerances, that generally are controllable with large numbersof units, however.

The relatively easily produced elastic connection between tilting tableand housing allows for friction-free and play-free positioning of anobject. This is especially important when, for example, opticalcomponents such as mirror elements must be dynamically moved with highfrequencies. Moreover, highly precise positioning of sensors, such asfor instance photodiodes, or sample manipulations are conceivable withthe inventive tilting table array.

One advantageous variant consists in providing a base plate (lockinglid), the tilting table array being positively or non-positively joinedto the base plate. In this connection, it is also conceivable to attachthe drive elements in the base plate, thereby joining them to thetilting table, so that there is also a positive or non-positive fithere.

For minimizing the individual elements and avoiding error sequences,however, it is advantageous to position and attach the drive elements inthe tilting table housing.

Depending on the application, one or more drive elements can be providedthat are arranged both symmetrically and asymmetrically on the tiltingtable adjacent to the elastic connection and that act thereon with thesame or different force.

For generating counter-forces, it is useful to provide one or aplurality of spring elements between the tilting table and the tiltingtable housing or between the tilting table and the base plate.

In the case of tilting table arrays in which the position of a mirrorelement is dynamically modified in the micro-range with high frequencies(oscillating mirror), it is useful to provide piezo-actors as driveelements.

Piezo-actors possess the outstanding characteristic that short switchingcycles with high power amplitudes are possible, even with small strokes(high accuracy of positioning).

Drive elements, such as drive elements that operate in accordance withthe principle of magnetostriction (magnetic coils) and/or in accordancewith the principle of differential transformation and/or in accordancewith the principle of oscillating capacitors and/or in accordance withthe principle of bending plates, are also conceivable. In addition,combinations with step motors and/or with hydraulic or pneumatic actorsare also possible.

When piezo-actors are used, it proves to be useful to connect the driveelements to the tilting table via a sphere, because working acounter-contour against the actor permits defined positioning relativeto the tilting table.

One variant of the inventive tilting table array consists in forming theelastic connection as a T-shaped joint. The rotation point of the jointcan also be placed directly beneath the object using the structuraldesign in terms of the height and depth as well as the position of thetransverse beam. This causes a reduction in the moment of inertia of thetilting table, together with a frequently desired increase in theresonant frequency of the tilting system (rapid switching).

Modification of the torsional rigidity by varying the geometricdimensions of the T-joint also influences the resonant frequency of thetilting system, but also limits the amplitude if only a dynamic force isavailable. Because the rigidity of the elastic connection also dependsdecisively on the material of the monolithic unit and the injectionmolding process itself, it is possible to define this parameter usingsuitable tool design during production of the monolithic unit. Tool setsthat can be used to determine the geometry of the T-joint can be easilyexchanged during the production process.

One advantageous embodiment of the inventive tilting table array,especially when mirrors are to be positioned, consists in forming theobject to be positioned, that is, the mirror, directly as a component ofthe monolithic unit, the surface of the tilting table comprising ametallic material being finely tooled such that it satisfies therequirements for an optical system. This is advantageous because evenfewer individual elements are necessary, thereby minimizing thecomplexity of assembly.

Furthermore, when a specially produced object, such as a mirror element,is received on the tilting table, it is advantageous to provide anobject receiver, wherein the connections between the object receiver andthe tilting table and between the object receiver and the object shouldbe designed as adhesive connections. The object receiver is usefullydesigned to be pot-shaped, its exterior base surface receiving theobject and its interior wall provided for attaching to speciallydesigned contours of the tilting table.

The advantage of this is that the object can initially be connected tothe object receiver by means of an adhesive substance in a relativelysimple manner. In a second assembly step, the object is then easilyadjusted and affixed to the object receiver without distortion occurringin the object. In addition, the “object—object receiver” unit can beeasily exchanged on the tilting table.

The tilting table movements, in connection with a compression springthat generates the counter-force, can lead to unpleasant vibrations, sothat one advantageous further development of the inventive arrayconsists in filling the interior space of the compression spring that isembodied as a spiral spring and that is limited by the tilting table andthe tilting table housing or the tilting table and the base plate and/orthe locking lid with an elastic shaping element.

The elastic shaping element usefully consists of a silicon rubbercompound that completely fills the interior space of the spiral spring,thus allowing for stress-free attenuation of the compound elementswithout requiring additional rubber elements subject to tolerances.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the inventive tilting table array is described ingreater detail using exemplary embodiments. The corresponding figuresshow:

FIG. 1 is a schematic view of the tilting table array with an elasticbending element,

FIG. 2 is a schematic view of the tilting table array with two elasticbending elements,

FIG. 3 is a top view of a tilting table array for an oscillating mirrorwith two elastic torsion elements,

FIG. 4 is a cross sectional view of the tilting table array according toFIG. 3 taken along section lines 4-4,

FIG. 5 is a cross sectional view of the tilting table array according toFIG. 3 taken along section lines 5-5, and

FIG. 6 depicts a torsion element in the form of a T-joint.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows, in schematic form, an embodiment of the inventive tiltingtable array, comprising a monolithic tilting table housing 1 with anintegrated tilting table 2 and an integrated elastic bending joint 3.Via two drive elements 5 and 6 arranged symmetrically to the elasticbending element 3 in a base plate 4, forces are transmitted to thetilting table 2 so that the position of an object 7 affixed to thetilting table can be modified in accordance with the control of thedrive elements 5 and 6.

FIG. 2 shows another exemplary embodiment of the design of a monolith,comprising a tilting table housing 8, a tilting table 9, as well as twoelastic bending elements 10 and 11. This embodiment is easily producedby injection molding or die-casting, simply using open/shut toolswithout additional couplers, so that the cost of tools can be keptextremely low.

An inventive tilting table array for micro-positioning (oscillatingmovement) a mirror element 12 is shown in the exemplary embodimentdepicted in FIGS. 3, 4 and 5, the same reference numbers identifyingidentical elements.

FIG. 3 shows the array in a top view from the side facing away from themirror element 12 to be positioned (without a base plate and/or lockinglid 13), comprising a tilting table housing 14 with an integratedtilting table 15. The tilting table 15 is connected to the tilting tablehousing 14 via two elastic torsion frames 16 and 17.

For the purpose of completing the positioning movement on the tiltingtable 15, that is, for generating the oscillating movement of the mirrorelement 12 (not shown in FIG. 3), a piezo-actor (piezo motor) 18 islocated in the tilting table housing 14 that acts on one side of thetilting table 15 via a sphere 19, thereby displacing the tilting table.The counter-force to the force of the piezo-actor 18 is generated by acompression spring 20 affixed to the tilting table 15 and the lockinglid 13, as can be seen in FIG. 4 (section 4-4 from FIG. 3).

An elastic shaping element 29 consisting of a silicone rubber mass isdisposed in the interior space of the compression spring 20 formed as aspiral spring, limited by the tilting table 15 and a spring guide pin 28molded to the locking lid 13.

Prior to the assembly of the locking lid 13, the silicone rubber mass isinjected into the interior space of the spiral spring 20. Duringassembly of the locking lid 13, the spring guide pin 28 dips, withoutforce, into the non-cross-linked silicone rubber mass that as a resultprecisely fills the interior space of the spiral spring 20. Then thesilicone rubber mass vulcanizes in a tension-free manner. Tempering theassembled array accelerates cross-linking.

Both the piezo-actor 18 and the locking lid 13 are connected to thetilting table housing 14 via screw elements 21 and/or 22.

For the purpose of affixing the mirror element 12 to the tilting table15, the surface of the tilting table 15 possesses two annular contours23 and 24 that support a pot-shaped object receiver 25 carrying themirror element 12.

The mirror element 12 is initially affixed to the pot-shaped objectreceiver 25 by means of tension-free adhesion. Then, as is more clearlyevident from FIG. 5 (section 5-5 taken from FIG. 3), the pot-shapedobject receiver 25 is placed onto the annular contours 23 and 24 and,following alignment in all degrees of freedom, connected to the tiltingtable 15 via an adhesive compound 26.

FIG. 6 shows a possible embodiment of the elastic connection between thetilting table 15 and the tilting table housing 14 in the form of aT-shaped joint 27 embodied as a torsion frame. The T-shaped joint 27,which, with regard to its torsional rigidity, depends on its geometricdimensions, such as depth T and length L, its position in the elasticconnection, and the material, is torsionally soft without bendingstiffness being significantly reduced. Low-frequency components ofmovement are blocked, thereby increasing the resonant frequency of thetilting system, which is decisive for rapid positioning procedures(switching procedures), especially in the case of optical elements. Theadjustment of the T-shaped joint 27 already takes place duringproduction of the monolithic unit in an injection molding process usingspecially manufactured variable tools. Mechanical retooling isunnecessary.

LIST OF REFERENCE NUMBERS

-   1, 8, 14 Tilting table housing-   2, 9, 15 Tilting table-   3,10, 11 Elastic bending element-   4 Base plate-   5, 6 Drive element-   7 Object-   12 Mirror element-   13 Locking lid (base plate)-   16, 17 Torsion frame-   18 Piezo-actor (piezo motor)-   19 Sphere-   20 Compression spring-   21, 22 Screw element-   23, 24 Annular contour-   25 Pot-shaped object receiver-   26 Adhesive mass-   27 T-shaped joint-   28 Elastic element/silicone rubber mass-   29 Spring guide pin

1. A tilting table array for micro-positioning an object, comprising atilting table carrying the object and connected to at least one driveelement and a tilting table housing that is coupled to the tilting tablevia an elastic connection, wherein the tilting table, the tilting tablehousing and the elastic connection comprise one monolithic unit.
 2. Thetilting table array according to claim 1, wherein the monolithic unitcomprises a metallic material.
 3. The tilting table array according toclaim 1, wherein the monolithic unit comprises a non-metallic material.4. The tilting table array according to claim 1, wherein the monolithicunit is an injection molded part, a diecast part or a combination of theforegoing.
 5. The tilting table array according to claim 1, wherein thetilting table housing is connected, to a base plate or a locking lidserving the purpose of dust protection
 6. The tilting table arrayaccording to claim 1, wherein the at least one drive element is affixedto the base plate or the locking lid and are positively ornon-positively connected to the tilting table.
 7. The tilting tablearray according to claim 1, wherein the drive element is attached in thetilting table housing.
 8. The tilting table array according to claim 1,wherein the elastic connection comprises at least one bending element,at least one torsion element or a combination of the foregoing.
 9. Thetilting table array according to claim 1, wherein the elastic connectioncomprises a torsion element comprises a T-shaped joint modifiable in itsgeometric dimensions and in its position.
 10. The tilting table arrayaccording to claim 9, wherein the T-shaped joint is adjustable byvariable tools during the injection molding process.
 11. The tiltingtable array according to claim 1, wherein the drive element is arrangedsuch that its dynamic effect is directed adjacent to the elasticconnection on the tilting table and wherein a counter-force is generatedby a compression spring.
 12. The tilting table array according to claim11, wherein the interior space of the compression spring is filled withan elastic shaping element for the purpose of reducing vibration in thearray.
 13. The tilting table array according to claim 12, wherein thecompression spring comprises a coil spring and the elastic shapingelement comprises a silicone rubber mass that completely fills theinterior space of the coil spring.
 14. The tilting table array accordingto claim 1, comprising at least two drive elements that are arrangedsymmetrically or asymmetrically to the elastic connection and that acton the tilting table with the same or different force.
 15. The tiltingtable array according to claim 14, in which the drive elements arearranged symmetrically.
 16. The tilting table array according to claim14, in which the drive elements act with unequal force.
 17. The tiltingtable array according to claim 1, wherein the drive elements comprisepiezo-actors.
 18. The tilting table array according to claim 1 whereinthe drive elements operate in accordance with the principle ofmagnetostriction, the principle of differential transformation, theprinciple of oscillating capacitors, the principle of bending plates,are step motors, hydraulic actors, pneumatic actors or a combination ofthe foregoing.
 19. The tilting table array according to claim 1,characterized in that the drive element is connected to the tiltingtable via a sphere.
 20. The tilting table array according to claim 1,wherein the object comprises an optical component.
 21. The tilting tablearray according to claim 1, wherein the tilting table supports an objectreceiver, wherein the connections between the object receiver and thetilting table and between the object receiver and the object are formedadhesive bonds.
 22. The tilting table array according to claim 21,wherein, the object receiver is pot-shaped and comprises an exteriorbase surface receiving the object and an interior wall for attaching toreceiving contours of the tilting table for the purpose of attachmentand assembly of the object to a reference plane.